A plurality of different sensor systems for sensing at least one property of a measured gas in a measured-gas space are believed to be understood. A “gas property” is to be understood in principle as any physical and/or chemical property of the measured gas, such that one or also several properties of the measured gas can be sensed. Qualitative and/or quantitative sensing of at least one property of a measured gas can be accomplished using such a sensor system, for example sensing of at least one gas component of the measured gas, in particular sensing of a gas component in an air/fuel mixture, and/or sensing of a particle concentration in the measured gas, in particular a particulate mass concentration. Alternatively or additionally, however, other properties of the measured gas can also be sensed.
A sensor system for sensing a gas property can be configured, for example as discussed in Konrad Reif (editor), “Sensoren im Kraftfahrzeug” [Sensors in motor vehicles], 2nd edition, 2012, pp. 160-165, as a lambda probe, an embodiment both as a two-point lambda probe and as a broadband lambda probe, in particular as a planar broadband lambda probe, being described. Using a lambda probe it is possible to identify a gas proportion of a gas mixture in a combustion chamber, for example the air/fuel ratio λ that indicates the ratio of air to fuel. With two-point lambda probes it is possible to identify the air/fuel ratio only within a narrow range, for stoichiometric mixtures (λ=1). With a broadband lambda probe, conversely, identification over a wide range of λ can occur. These above-described lambda probes encompass a sensor element, usually a ceramic solid electrolyte which may be made of zirconium dioxide and yttrium oxide, or also solid layers, which may be made of zirconium dioxide. The sensor element is surrounded by a protective tube for protection from damage.
In sensor systems, for example in a lambda probe or, for example, in a particle sensor that can have the same geometric configuration as a lambda probe, for measuring a property of a measured gas in a measured-gas space, seals between various components of the sensor systems are categorically necessary. U.S. Pat. No. 6,453,726, for example, discusses a gas sensor having a sensor element partly surrounded by a housing and by an upper protective shield. A U-shaped seal is disposed between the upper protective shield and the housing in order to protect the sensor element. U.S. Pat. No. 7,222,408 furthermore describes a gas sensor having a sensor element that is disposed in hermetically sealed fashion in a housing. Gas sealing of a measured-gas space and of a reference-gas space inside the gas sensor is enabled by a crimping of the housing.
According to the related art, it is understood that a probe for sensing at least one gas property is introduced into a measured-gas space through a receiving element in a wall of the measured-gas space. A seal is disposed between the probe and the measured-gas space in order to prevent emergence of the measured gas from the measured-gas space. The seal can be configured, for example, as in DE 60 2005 002 375 T2, which proposes to ensure leak tightness of a connection between a probe and an exhaust manifold using a circular ring having the cross section of an outward-opening U.
Patent document DE 10 2012 205 618 A1 furthermore proposes a sensor that has a tubular sleeve made of metal as well as a tubular attachment element. The sleeve has a flange that is present in front of the attachment element and projects outward beyond a radially internal surface of the attachment element. A corner of the flange comes into contact with an oblique surface of the attachment element.
Patent document DE 100 22 958 A1 furthermore discusses a gas sensor, having a metallic housing, that is fastened by way of a hollow bolt in a measurement opening having a measured gas. Provided on a side of the housing which faces toward the measurement opening is a conically shaped surface with which the gas sensor sits on a conically shaped counter-surface. The conically shaped surfaces are at the same angle with respect to a longitudinal axis of the housing. A planar seal of this kind as recited in the existing art, as discussed e.g. in DE 60 2005 002 375 T2 with a sealing ring between a probe and a measured-gas space and in DE 100 22 958 A1, is disadvantageous, however, since a planar seal has a large sealing area. This makes possible only a poor sealing effect.
A seal of this kind having an additional sealing ring as recited in the existing art is additionally disadvantageous because installation of a probe, for example in an exhaust gas duct of an internal combustion engine, using a sealing ring can be complex and difficult, and it is moreover possible to lose the sealing ring during installation. With a planar seal having no sealing ring, a high degree of parallelism and flatness must be ensured for the mutually abutting surfaces. High costs for production, and high sensitivity to damage, can result therefrom.
A sensor system that exhibits excellent leak tightness between a probe and a measured-gas space, and that enables economical production and robustness for the seal, would therefore be desirable.